fix(comp:modal): update modal content with update doesn't work

[sallerli1]

PR Checklist

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• The commit message follows our guidelines
• Tests for the changes have been added/updated or not needed
• Docs and demo have been added/updated or not needed

What is the current behavior?

调用 userModal 创建的 modalRef 的update 更新 content，无法触发更新

What is the new behavior?

修复以上问题

Other information

添加私有属性 __content_prop用来传递content

[idux-bot]

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[codecov]

Codecov Report

Merging #1270 (3cc98b4) into main (99e4ddd) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1270   +/-   ##
=======================================
  Coverage   93.05%   93.05%           
=======================================
  Files         320      320           
  Lines       29469    29471    +2     
  Branches     3344     3345    +1     
=======================================
+ Hits        27422    27424    +2     
  Misses       2047     2047           

Impacted Files	Coverage Δ
packages/components/modal/src/ModalBody.tsx	97.46% <100.00%> (ø)
packages/components/modal/src/ModalProvider.tsx	97.05% <100.00%> (-0.09%)	⬇️
packages/components/modal/src/types.ts	100.00% <100.00%> (ø)
packages/components/tree/src/Tree.tsx	95.13% <0.00%> (+0.06%)	⬆️

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[danranVm]

感觉这种处理方式不是很优雅，不知道有没有更好的处理方案。